Outer's superclass' method is now inaccessible from nested

Also the diagnostic error message reported the wrong nested class name: it
should be the nested class in the hierarchy which is static, not the class of
the scope where we're checking the accessibility

compiler/testData/diagnostics/tests/inner/outerSuperClassMember.kt

@@ -0,0 +1,9 @@
+open class Base {
+    fun foo() {}
+}
+
+class Derived : Base() {
+    class Nested {
+        fun bar() = <!INACCESSIBLE_OUTER_CLASS_EXPRESSION!>foo()<!>
+    }
+}